Kinetic studies on the formation of ternary complexes in the reaction of diaquo-nitrilotriacetato-nickelate(II) and diaquo-anthranilato-N,N′-diacetato-nickelate(II) with amino acids in aqueous solution

Summary Kinetics of formation of ternary complexes from diaquo-nitrilotriacetatonickelate(II), [Ni(nta)(H₂O)₂]^–, and diaquoanthranilato-N, N-diacetatonickelate(II), [Ni(ada)-(H₂O₂] and amino acids have been studied by a pH indicator method using stopped-flow spectrophotontetry. The results conform to 1/k_obs=1/k+[H⁺]/kK·T_L, where K is the equilibrium constant for the formation of [Ni(A)(-L)(H₂O)]^2–(A=nta^3– or ada^3–) and k is the specific rate constant for the subsequent rate-determining ring closure leading to [Ni(A) (=L)]^2–. For the different amino acids, the k values decrease in the sequence: glycine>-alanine>L-phenylalanine>L-Valine>L-methionine>-alanine>sarcosine>N,N-dimethylglycine, and areca. 1000 times smaller than the k values for complexation of [Ni)(nta)(H₂O)₂]^– with monodentate ligands, such as NH₃ and imidazole. The spread of k values is much less than the pK_a values of the amino acids, and can be accounted for on the basis of the proposed mechanism. The relative rates are enthalpy controlled and high negative S values are commensurate with ring closure as the rate-determining step.     

Volumetric study on a Co(III) rotaxane complex in aqueous solutions at 25°C

Résumé The standard partial molar volumes have been determined for [(en)₂ClCo(III)(don) Co(III)CL(en)₂] Br₄-[-CDX]-rotaxane (Rotaxane) and its component compounds, [(en)₂ClCo(III)(don)Co(III)Cl(en)₂] Br₄ (Co(III)-II), and -CDX, in aqueous solution at 25°C V^o (Rotaxane) is smaller than the sum of V^o (CO(III)-II) and V^o (-CDX) by about 28 cm³-mol^–1. Some estimations were attempted; the number of methylene groups in the cavity of -CDX, was estimated to be six and the number of water molecules expelled from -CDX cavity by hydrocarbon chain of the Rotaxane, is around four.     

Synthesis and base hydrolysis kinetics of the nitrile complexes [Co(tetren)NCR]3+ (R=Me,Ph and p-MeOC6 H4) and the synthesis and kinetics of formation of the tetrazolato complexes [Co(tetren)N4R]2+ (R=Me and Ph; tetren=1,11-diamino-3,6,9-triazaundecane) by reaction with azide ion

The N-bonded nitrile complexes -[Co(tetren)NCR]³⁺ (R=Me, Ph, p-MeOC₆ H₄) have been prepared by the reaction of -[Co(tetren)OH₂]³⁺ with the corresponding nitrile. The kinetics of base hydrolysis have been studied by pH-stat methods. The reactions involve an SN₁CB displacement of the nitrile to give the hydroxopentamine; nucleophilic attack at the nitrile carbon to give the corresponding carboxamido complex does not occur. NaN₃ reacts with the nitrile complexes in slightly acidic solution (pH ca. 5.7) to give the tetrazolato complexes [Co(tetren)N₄ R]²⁺ (R=Me, Ph) which have been characterised. The reaction of azide ion with -[Co(tetren)NCMe]³⁺ has been studied kinetically. The reaction is biphasic involving the initial rapid formation of the N₁-bonded (5-methyltetrazolato) pentaminecobalt(III) complex with k=2×10^–2dm³ mol^–1s^–1 at 25°C followed by the slow isomerisation to the N₂-bonded complex with k=3.5×10^–5s^–1 at pH 5.7.     

Structure and configuration of a new diterpenoid lactone fromLagochilus hirsutissimus

The epigeal part of the plantLagochilus hirsutissimus has yielded a new diterpenoid lactone — lagohirsidin, C₂₂H₃₄O₅, mp 144–145°C, [] _D ²² – 17.5° (c 1; ethanol). Reduction with LiAlH₄ has yielded a diol C₂₂H₃₈O₅, mp 165–166°C [] _D ²⁰ –1.2 (c 0.6; ethanol). Acid hydrolysis of the diol has led to the formation of lagochilin, C₂₀H₃₆O₅, mp 167–168°C, [] _D ²⁰ –3.9° (c 1; ethanol). The synthesis of lagohirsidin from lagochilin has been effected.V. I. Lenin Tashkent State University. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 788–792, November–December, 1979.     

Synthesis and magnetic properties of trinuclear chromium(III)palladium(II)-chromium(III) complexes bridged by extended dioximato groups

Summary Heterotrinuclear Cr^III-Pd^II-Cr^III complexes of formulae [Cr(salen)-Pd(dmg)₂-Cr(salen)]·H₂O (1), [Cr(salen)-Pd(-BD) ₂-Cr(salen)]·H₂O (2) and [Cr(salen)-Pd(-FD) ₂-Cr(salen)]·2H₂O (3) [dmg^2- =dimethyl-glyoximato, (-BD)^2/2- = -benzyldioximato, (-FD)^2/2- = -furildioximato and salen^2– = N,N-ethylenebis(salicylideneiminate)] have been prepared and characterized by elemental analysis, i.r. and electronic spectroscopies, and molar conductances. These complexes are thought to contain extended diomixato bridges. The magnetic properties of complex (1) has been investigated over the 80–300 K range and corresponds to what is expected for an antiferromagnetic Cr^III-Cr^IIIi pair with S _Cr = 3/2 and S _Pd = 0 (Pd²⁺ is a diamagnetic in a square-planar environment) local spins. The exchange integral (J) was evaluated as -3.38cm^–1 using the spin Hamiltonians = -2J _{A B}(S _A = S _B = 3/2).     

Kinetic studies on the formation of ternary complexes in the reaction of diaquonitrilotriacetatonickelate(II) with amino acids in aqueous solution

Summary Kinetics of formation of ternary complexes in the reaction of Ni(NTA)(H₂O) ₂ ^– with several amino acids, LH^± (glycine, -alanine, -alanine, L-valine and L-phenylalanine) have been studied by a pH indicator method using stopped-flow spectrophotometry. The results conform to 1/k_obs = 1/k + [H⁺]/ kKT_L where K is the equilibrium constant for formation of Ni(NTA)(–L)(H₂O)^2–, and k is the specific rate constant for the subsequent rate-determining ring-closure step leading to Ni(NTA)(=L)^2–. For the different amino acids studied, the k values decrease in the sequence: glycine > -alanine > L-phenylalanine > L-valine > -alanine. These k values areca. 1000 times lower than the values for complexation of Ni(NTA)(H₂O) ₂ ^– with NH₃ and imidazole and the spread in k values is much less than the pK_a values of the amino acids. The relative rates are enthalpy controlled and the S values are highly negative in conformity with ring closure as the rate determining step.     

Glycosylation of triterpenoids of the dammarane series I. 20(S),24(R)-epoxydammarane-3α-12β,25-triol 25-O-β-D-glucopyranoside

The glycosylation of 3,12-diacetoxy-20(S),24(R)-epoxydammaran-25-ol with -acetobromoglucose under the conditions of Helferich's modification and with D-glucose tert-butyl orthoacetate under the conditions of the orthoester method gives a high yield (60–64%) of the hexacetate of the -D-glucoside at the tertiary hydroxy group of 20(S),24(R)-epoxydammarane-3,12,25-triol (III) with mp 207–209°C (ethanol), [] _D ²⁰ -20.9 (c 1.0, CHCl₃). Saponification with 10% KOH in methanol gives the free 20(S),24(R)-epoxydammarane-3,12,25-triol 25-O--D-glucoside (V) (yield 90%) with mp 275–279°C (methanol), [] _D ²⁰ +11.4° (c, 1.0, C₅H₅). The results of IR and¹H and¹³C NMR spectroscopy and of elementary analysis are given.Pacific Ocean Institute of Bioorganic Chemistry of the Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 205–208, March–April, 1980.     

Compounds of imidazoles with ruthenium(III) chloride

Summary Reaction of ruthenium(III) chloride with imidazole(Im) and different substituted imidazoles,viz. N-methylimidazole (N-MeIm), 2-methylimidazole(2-MeIm), 4-methylimidazole (4-MeIm),N-vinylimidazole(N-VIm), 2-methyl- 1-vinyl-imidazole(2-Me-1-VIm), 1,2-dimethylimidazole(1,2-Me,Im), 2-ethylimidazole(2-EtIm) and 2-ethyl-4(5)-methylimidazole (2-Et-4(5)-MeIm] yield products of the types [Ru₂L₄Cl₆] · 2 H₂O (L = N-VIm or 4-MeIm), [Ru₂L₄Cl₆] · 4 H₂O (L = Im or 2-Et-4(5)-MeIm), [Ru₂L ³ (H₂O)Cl₆] (L =N-MeIm or 2-MeIm), [Ru₂L ² (H₂O)₂Cl₆] (L = 1,2-Me₂Im or 4-MeIm), [Ru(2-Me-1-VIm)₃Cl₃] · H₂O and [Ru(2-EtIm)₃(H₂O)Cl₂]. These compounds were characterised by elemental analyses, conductometric measurements, i.r. and electronic spectral analyses. Magnetic moments range from 1.01 to 1.9 B.M. The e.s.r. spectra and g values of some of the compounds are indicative of high distortion.     

Triterpene glycosides of alfalfa. III. Medicoside I

On the basis of chemical transformations and with the aid of physicochemical results, the structure of glycoside I isolated from the roots of the plantMedicago sativa has been established as hederagin 3-O-[O--L-arabinopyranosyl-(1 2)--D-glucopyranosyl-(1 2)--L-arabinopyranoside] 28-O--D-glucopyranoside. Compound (I), C₅₂H₈₄O₂₂, mp 210–212°C, [] _D ²¹ +38.4° (c 1.48; methanol). Acid hydrolysis of (I) led to hederogenin (II) — C₃₀H₄₈O₄, mp 326–330°C, [] _D ²³ +84.2° (c 0.19; pyridine. The Hakomorimethylation of glycoside (I) yielded the permethylate (IV) — C₆₅H₁₁O₂₂ [] _D ²³ +41.6° (c 1.79; methanol). The GLC analysis of the products of the methanolysis of compound (IV) showed the presence of 3,4,6-tri-O-methyl-D-glucopyranose, 2,3,4,6-tetra-O-methyl-D-glucopyranose, 3,4-di-O-methyl-L-O-arabinopyranose, and 2,3,4-tri-o-methyl-L-arabinopyranose. The alkaline hydrolysis of glycoside I gave compound (III) with mp 230–233°C, [] _D ²¹ +35.2° (c 0.21; methanol), which was identified as medicoside C. Details of the PMR spectrum are given for compound (IV) and of the IR spectrum for compound (I).Institute of the Chemistry of Plant Substances of the Uzbek Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 607–610, September–October, 1986.     

Withasteroids ofPhysalis VI.1H and13C NMR spectra of withasteroids ixocarpalactone A and ixocarpanolide

The¹H and¹³C NMR spectra of two withasteroids isolated fromPhysalis ixocarpa Brot. have been studied in detail. Their spectral characteristics are discussed. A comparison of the results obtained has led to the identification of a withasteroid with the composition C₂₈H₄₀O₈, mp 291–292°C (from methanol) as ixocarpalactone A, in spite of some difference in its physical constants. The other compound, with mp 252–253°C (from methanol), had the composition C₂₈H₄₀O₆, [] _D ²⁰ +27±4°, is new and has been called ixocarpanolide. The structure of 5,20R-dihydroxy-1-oxo-6, 7-epoxy-22R-witha-2-enolide has been proposed for it.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 326–332, May–June, 1986.     

Naphthyl-(2-pyridylmethylene)amine complexes of silver(I) and ruthenium(II): synthesis,spectral studies and electrochemical behaviour

Pyridine-2-carboxaldehyde reacts with /-naphthylamine to give /-naphthyl-(2-pyridylmethylene)amine [-L (1), -L (2)]. L belongs to the unsymmetric diimine (—N=C—C=N—) family which can form five–membered chelate rings with metal ions. {donor centers are abbreviated as N[N(Py)] and N [N(nap)]} [Ag(L)₂]⁺ complexes were prepared and characterized by spectroscopic data. The reaction between L and RuCl₃ in boiling EtOH yielded green and blue–green compounds of composition RuCl₂(L)₂. I.r., u.v.–vis. and ¹H-n.m.r. data determined the stereochemistry of the complexes as trans-cis-cis (green) and cis-trans-cis (blue–green) according to the sequence of the coordination pair of Cl, N [N(Py)] and N [N(nap)]. Upon treatment of Ag(L)₂ ⁺ with Ru(bpy)₂Cl₂ in alcoholic suspension the ternary complexes, [Ru(bpy)₂(L)](ClO₄)₂, were isolated and characterized by spectroscopic data. [Ru(bpy)(L)₂](ClO₄)₂ complexes were synthesized similarly from ctc-Ru(L)₂Cl₂ and 2,2-bipyridine (bpy) in the presence of AgNO₃ and NaClO₄. These complexes show well-defined m.l.c.t transitions in the visible region. The sterochemistry of the complexes was established by ¹H-n.m.r. data. Cyclic voltammetry shows a high potential Ru^III/Ru^II couple and follows the order: [Ru(bpy)(L)₂]²⁺ > [Ru(bpy)₂(L)]²⁺ > Ru(-L)₂Cl₂ > Ru(-L)₂Cl₂.     

Reactions ofbis(isopropylxanthato)nickel(II) with N-donor ligands

Summary Complexes of Ni^II with isopropylxanthate and Lewis bases as mixed N-ligands of composition [Ni(i-prxa)₂(L)] and [Ni(i-prxa)₂(L)₂] have been prepared, where i-prxa = i-C₃H₇OCS ₂ ^- , and L = ethylenediamine, 2,2-bipyridine, 1,10-phenanthroline or 5-nitro-1,10-phenanthroline, and L =-picoline or benzothiazole. On the basis of their chemical analyses, i.r. and electronic spectra, magnetic measurements, thermal analyses and molar conductivities, an octahedral structure is proposed. The crystal and molecular structures of [Ni(i-prxa)₂(phen)] and [Ni(i-prxa)₂(btz)₂] were determined, showing oncis-octahedral andtrans-octahedral coordination spheres, respectively, with an NiS₄N₂ chromophore.     

The solid state and solution chemistry of dichlorobis(α-picoline)-cobalt(II)

Summary The thermal decomposition of [CoCl₂(-pic)₂] was investigated over the 108°C to 222°C range and the Intennediates CoCl₂(-pic) (s) and CoCl₂ (s) were observed, with the evolution of (-pic) (g). Quantitative thermodynamic and kinetic data were obtained by performing dynamic and isothermal studies on the complex Additional thermodynamic data were obtained by studying the CoCl₂/-pic system in acetone. The effect of the methylsubstituent on the metal-donor-N bond as well as on the thermodynamic quantities were discussed.     

Kinetics of chlorine isotope exchange reaction between sodium chloride-36 and triphenyltin chloride in mixed solvents

Isotope exchange reaction between NaCl-36 and triphenyltin chloride in dioxane-water (8020% w/w) and ethanol-water (9010% w/w) mixed solvents has been studied at 25, 35 and 50 °C. The exchange reaction was found to proceed via a bimolecular S_N2, limiting mechanism with reaction rates depending on the solvent used. Inhibition of the exchange in ethanol-water is probably due to solvation of chloride ion through hydrogen bond formation. The rate laws for the exchange reactions are: R_e=3.24×10⁹ e^–65550/RT [Rh₃SnCl] [NaCl] in dioxanewater and R_e=6.61×10⁸ e^–69600/RT [Ph₃SnCl] [NaCl] in ethanol-water, where is the degree of dissociation of NaCl and R_e is the rate of exchange in mol l^–1 s^–1. The activation parameters H^*, S^* and G^* are reported.     

Synthesis and characterization of cobalt(II), nickel(II), copper(II) and zinc(II) complexes with acetylacetone bis-benzoylhydrazone and acetylacetone bis-isonicotinoylhydrazone

Summary Acetylacetone bis-benzoylhydrazone (PhCONHN=CMe)₂ CH₂(LH₂) and acetylacetone bis-isonicotinoylhydrazone (NC₅H₄CONHN=CMe)₂CH₂(LH₂) complexes of the types [ML] and [ML] (M = Co^II, Ni^II, Cu^II or Zn^II) have been prepared and characterized. All the complexes are non-electrolytes and the cobalt(II) complexes are lowspin, the nickel(II) complexes are diamagnetic and the copper(II) complexes are paramagnetic. The ligands chelate via two C=N groups and two deprotonated enolate groups. The e.s.r. spectra of the copper(II) complexes indicate a tetragonally distorted dimeric structure. The X-ray diffraction parameters for [CoL] and [NiL] correspond to a tetragonal crystal lattice.     

5,6-Dihydro-1,4-thiazine durch Einwirkung von Propylenimin auf α-Mercaptoketone

Zusammenfassung Die Umsetzung von -Mercaptoketonen mit Propylenimin führt zu 2,3-disubstituierten 5-Methyl-5,6-dihydro-4H-(bzw. 2H)-1,4-thiazinen. Sie reagieren im Gegensatz zu den in Stellung 5 nicht substituierten Äthylenimin-Reaktionsprodukten nicht mit einem weiteren Mol--Mercaptoketon unter Bildung von Thiazolo[2,3-c]-1,4-thiazinen.Die Dihydrothiazine lassen sich mit Ameisensäure oder NaBH₄ zu sterisch identischen Thiomorpholinen hydrieren; in einigen Fällen gelingt diese Hydrierung auch mit H₂S, wobei jedoch die stereoisomeren Thiomorpholine gebildet werden. Thiazolo [2,3-c]-1,4-thiazine ergeben bei der Behandlung mit Ameisensäure oder NaBH₄ stereoisomere Perhydro-thiazolo[2,3-c]-1,4-thiazine.Teil der DissertationH. Diem, T. H. Aachen, 1962.     

Electronic structure of the Fe3S4 cluster and its quasi-aromaticity

The localized molecular orbitals and their energy levels for the clusters [Fe₃S₄(SH)₃]^2–, [(HS)₃Fe₃S₄·Ni(PH₃)]^2–, [Mo₃S₄(OH₂)₉]⁴⁺, and [Mo₃S₄·Ni]⁴⁺ have been calculated by mean of the Edmiston-Ruedenberg energy localization technique under the CNDO/2 approximation in order to reveal the resemblance between [Fe₃S₄]⁺ and [Mo₃S₄]⁴⁺ in the geometrical configurations and the addition reactivities with heterometal atoms. It is shown that in these two cluster species with core {M ₃(₃-S)(-S)₃} of similar structure (M = Mo, Fe) there exist three synergically connected three-centered two-electron (M-S-M) -bonds around the puckered six-membered {M₃S₃} rings on account of delocalization of a lone electron pair on each bridging S atom; these (M-S-M) -bonds are thus capable of forming cubane-like heterometal clusters with intruder metal atoms through the ( M) bonding. It is therefore seen that unlike the [Mo₃S₄]⁴⁺ with appreciable bonding between the Mo atoms, the extra d-electrons on the metal atoms in the [Fe₃S₄]⁺ cluster are localized on the Fe atoms, exhibiting an electronic structure significantly different from that of the [Mo₃S₄]⁴⁺ cluster.     

Triterpene glycosides and their genins fromThalictrum foetidum. V. Structure of cyclofoetoside B

A new glycoside (cyclofoetoside B) (I) has been isolated from the epigeal part of the plantThalictrum foetidum L. (Ranunculaceae). On the basis of chemical transformations and with the aid of physicochemical characteristics it has been established that cyclofoetoside B is 24S-cycloartane-3, 16, 24, 25, 29-pentaol 3-O--L-arabinopyranoside 16-O-[O--L-rhamnopyranoside-(1 6)--D-glucopyranoside], C₄₇-H₈₀O₁₇, mp 194–197°C (methanol); [] _D ²⁴ +15.7 ± 2° (c 0.88; pyridine). The enzymatic hydrolysis of (I) has yielded cyclofoetigenin B (III), 24S-cycloartane-3,16,24,25,29-pentaol 16-O--D-glucopyranoside, (IV), C₃₆H₆₂O₁₀, mp 223–225°C (acetone), [] _D ²⁴ +37 ± 2° (c 0.97; methanol) and 24S-cycloartane-3,16,24,25,29-pentaol 16-O-[O--L-rhamnopyranosyl-(1 6)--D-glucopyranoside, C₄₂H₇₂O₁₄, mp 229–231°C (methanol), [] _D ³⁰ +41 ± 2° (c 0.7; methanol). Details of the IR and¹H and¹³C NMR spectra of the compounds are given.Irkutsk Institute of Organic Chemistry, Academy of Sciences of the USSR. Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Trashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 341–345, May–June, 1986.     

Protonation of pyrrolo [1,2-α] Pyrimidine derivatives

The protonation of pyrrolo [1,2-] pyrimidine and 6, 7, 8, 9-tetrahydropyrimido [1, 2-] indole derivatives in CF₃COOH (at –15 to +25° C) and in CF₃COOH/H₂SO₄ (at 25°) was studied by PMR spectroscopy. The investigated compounds form monocations, the structure of which corresponds to the addition of a proton to the carbon atom of th pyrrole fragment in the position to the bridge nitrogen atom.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 686–692, May, 1976.     

Phytoecdysones ofSilene praemixta. I. Silenosterone

In addition to known ecdysteroids (2-deoxy--ecdysone and 2-deoxyecdysterone) fromSilene praemixta (Caryophyllaceae) we have isolated new ones — premixisterone and selenosterone (I), C₂₇H₄₂O₇, mp 115–117°C (from MeOH), [] _D ²⁸ +86.9 ± 2° (c 0.92, MeOH), yield 0.003%. The acetylation of (I) with (CH₃CO)₂O in Py gave 22-acetyl-selenosterone (II), C₂₉H₄₄O₆, mp 210–212°C (MeOH-C₆H₁₄), [] _D ²⁷ +45.5 ± 3° (c 0.16; MeOH). On the basis of physiocochemical and spectral characteristics it has been established that (I) has the structure of 14,22R,25-trihydroxy-5-cholest-7-ene-3,6-dione. The IR, PMR, and mass spectra of (I) and (II) are presented.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 793–797, November–December, 1979.